1. You can query data in a database (ask it questions).
2. You can look up data from a database relatively rapidly.
3. You can relate data from two different tables together using JOINs.
4. You can create meaningful reports from data in a database.
5. Your data has a built-in structure to it.
6. Information of a given type is always stored only once.
7. Databases are ACID.
8. Databases are fault-tolerant.
9. Databases can handle very large data sets.
10. Databases are concurrent; multiple users can use them at the same time without corrupting the data.

In short, you benefit from a wide range of well-known, proven technologies developed over many years by a wide variety of very smart people.

1. You can query data in a database (ask it questions).
2. You can look up data from a database relatively rapidly.
3. You can relate data from two different tables together using JOINs.
4. You can create meaningful reports from data in a database.
5. Your data has a built-in structure to it.
6. Information of a given type is always stored only once.
7. Databases are ACID.
8. Databases are fault-tolerant.
9. Databases can handle very large data sets.
10. Databases are concurrent; multiple users can use them at the same time without corrupting the data.
11. Databases scale well.

In short, you benefit from a wide range of well-known, proven technologies developed over many years by a wide variety of very smart people.

If you're worried that a database is overkill, check out SQLite.